External fan

ABSTRACT

An external fan is mounted on a chassis and includes a retaining stage and a ceramic axis. The retaining stage is arranged on one external side of the chassis and includes a base and a hollow rod erecting on the base. A stator is arranged outside the hollow rod. The ceramic axis passes into the hollow rod and includes a first end connected to a rotator wrapped outside the stator and a second end extending out of a bottom of the base and connected to a blade inside the chassis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved external fan, and moreparticularly to an improved external fan suitable for operating externalto a closed and high-temperature environment.

2. Description of Related Art

FIG. 1 shows an exploded view of a prior art fan structure, which is anexternal axial fan. The external axial fan comprises a hollow casing 1 awith a rounded chamber 10 a. A pivotal stage 11 a is arranged on abottom face of the rounded chamber 10 a and a hollow rod 12 a isprojected from the center of pivotal stage 11 a. A stator 2 a is capedto the hollow rod 12 a and is connected to a control circuit 20 a. Thestator 2 a comprises a plurality of metal plates 21 a stacked togetherand an induction coil 22 a wrapped around the metal plates 21 a. Arotator 3 a comprises a hub 30 a, a plurality of blades 31 a and amagnet (not shown) arranged in the hub 30 a. An axis (not shown) isarranged at center of the hub 30 a and passes bearings 13 a arranged inthe hollow rod 12 a such that the rotator 3 a is placed in the roundedchamber 10 a.

The fan is generally placed outside the working environment and blowscool air into the working environment and ejects hot air from theworking environment to cool the working environment. However, for aclosed working environment, an internal fan is also required to producea convection effect for heat exchange between working environment andexternal ambience. The design of prior art fan is not suitable forhigh-temperature operation. The operation of fan will be unstable andthe lifetime is limited for high-temperature operation. Moreover, theblade size is limited when the blades are fixed on the hub and thedesign of the blade is also limited.

SUMMARY OF THE INVENTION

The present invention provides an improved external fan suitable foroperating external to a closed and high-temperature environment. Thestator and the rotator of the fan are external to the high-temperatureenvironment and the fan comprises a ceramic axis made of heat-resistantand durable material. Therefore the lifetime and stability of the fancan be ensured.

Accordingly, the present invention provides an external fan mounted on achassis and including a retaining stage and a ceramic axis. Theretaining stage is arranged on one external side of the chassis andincludes a base and a hollow rod erecting on the base. A stator isarranged outside the hollow rod. The ceramic axis passes into the hollowrod and includes a first end connected to a rotator wrapped outside thestator and a second end extending out of a bottom of the base andconnected to a blade inside the chassis.

BRIEF DESCRIPTION OF DRAWING

The features of the invention believed to be novel are set forth withparticularity in the appended claims. The invention itself however maybe best understood by reference to the following detailed description ofthe invention, which describes certain exemplary embodiments of theinvention, taken in conjunction with the accompanying drawings in which:

FIG. 1 shows an exploded view of a prior art fan structure.

FIG. 2 shows an exploded view of the present invention.

FIG. 3 shows a perspective view of the present invention.

FIG. 4 is a sectional view of the present invention.

FIG. 5 shows an application of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 2 to 4, the present invention provides animproved external fan. As shown in FIG. 5, the external fan is mountedto a closed chassis of an electronic device during use and provides airconvection for the closed chassis. The external fan comprises aretaining stage 1 and a ceramic axis 2.

The retaining stage 1 comprises a base 10 for assembling the retainingstage 1 and the base 10 comprises a plurality of flanges 100 on outerperipheral thereof. Moreover, each of the flanges 100 comprises aclamping hole 101 through which screwing units 50 are assembled. Ahollow rod 11 is projected at center of the base 10 and through thecenter of the base 10. A stator 3 is provided outside the hollow rod 11and is connected to a control circuit 32. The stator 3 comprises aplurality of metal plates 30 stacked together and an induction coil 31wrapped around the metal plates 30. When the control circuit 32 supplieselectrical current to the induction coil 31, the induction coil 31excites magnetic field.

The ceramic axis 2 is resistant to high temperature and passes throughthe hollow rod 11. A plurality of bearings 20 is provided in the hollowrod 11 and caped to the ceramic axis 2. Both ends of the ceramic axis 2expose out of the hollow rod 11 with one end connected to a rotator 4.The rotator 4 wraps outside the stator 3 and comprises a hub 40 and amagnetic unit 41 provided on inner face of the hub 40. The one end ofthe ceramic axis 2 is connected to bottom center of the hub 40; anotherend of the ceramic axis 2 extends out of a bottom of the retaining stage1 and comprises a thread portion 21 for screwing to a blade 22. Theblade 22 is made of material resistant to high temperature. The spiraldirection of the thread portion 21 is opposite to the rotation directionof the rotator 4.

The external-rotation fan according to the present invention can beconstructed by above-mentioned manner.

As shown in FIG. 5, the fan is mounted to a chassis 5 of an electronicdevice from external direction by engaging the flanges 100 into thechassis and screwing the screwing unit 50 (such as screw or bolt) intothe clamping hole 101. Moreover, the ceramic axis 2 is inserted into thechassis and the blade 22 can be mounted on the ceramic axis 2 by thethread portion 21 subsequently. The blade 22 is operated for airconvection inside the closed chassis, whereby the air inside the chassis5 has sufficient heat exchange for heat dissipation.

The blade 22 is designed to separate with the hub 40. Therefore theblade 22 could have larger size. The shape of the blade 22 is notlimited by the hub 40 because the blade 22 is extended from the ceramicaxis 2 instead of the hub 40. The stator 3 and the rotator 4 of the fanare external to the chassis 5 and are exempted from high temperature inthe chassis 5 during operation. Therefore the lifetime and stability ofthe fan can be ensured.

Although the present invention has been described with reference to thepreferred embodiment thereof, it will be understood that the inventionis not limited to the details thereof. Various substitutions andmodifications have suggested in the foregoing description, and otherwill occur to those of ordinary skill in the art. Therefore, all suchsubstitutions and modifications are intended to be embraced within thescope of the invention as defined in the appended claims.

1. An external fan mounted on a chassis, comprising: a retaining stagearranged on one external side of the chassis and comprising a base and ahollow rod erecting on the base, a stator arranged outside the hollowrod; and a ceramic axis passing into the hollow rod and comprising afirst end connected to a rotator wrapped outside the stator and a secondend extending out of a bottom of the base and connected to a bladeinside the chassis.
 2. The external fan as in claim 1, wherein the basecomprises a plurality of flanges, each of the flanges comprises aclamping hole through which a screwing member is engaged.
 3. Theexternal fan as in claim 1, wherein the hollow rod comprises a pluralityof bearings therein and capped on the ceramic axis.
 4. The external fanas in claim 1, wherein the second end of the ceramic axis comprises athread portion for screwing to the blade.
 5. The external fan as inclaim 4, wherein a spiral direction of the thread portion is opposite toa rotation direction of the rotator.
 6. The external fan as in claim 1,wherein the blade is extended from a portion near the ceramic axis.